高等学校化学学报

高等学校化学学报 ›› 2000, Vol. 21 ›› Issue (12): 1896.

• 论文 • 上一篇    下一篇

微量吸附量热技术研究Pd-Cu/SiO2的表面吸附

李明时, 葛欣, 邹琥, 沈俭一   

  1. 南京大学化学系, 南京 210093
  • 收稿日期:1999-12-01 出版日期:2000-12-24 发布日期:2000-12-24
  • 通讯作者: 沈俭一(1956年出生),博士,教授,从事吸附与多相催化研究.Email:jyshen@netra.nju.edu.cn.
  • 基金资助:

    国家自然科学基金(批准号:29973013);国家重点基础研究发展规划项目(G199022408)资助

Microcalorimetric Studies of Adsorption on the Surface of Pd-Cu/SiO2

LI MingShi, GE Xin, ZOU Hu, SHEN JianYi   

  1. Department of Chemistry, Nanjing University, Nanjing 210093, China
  • Received:1999-12-01 Online:2000-12-24 Published:2000-12-24

PDF (PC)

摘要： 应用微量吸附量热技术研究了室温下H2,CO,O2和C2H4在m(Pd)/m(SiO2)=2%,m(Pd,Cu)/m(SiO2)[n(Pd)/n(Cu)=1/1]=2%,m(Pd,Cu)/m(SiO2)[n(Pd)/n(Cu)=1/4]=2%和m(Cu)/m(SiO2)=8%催化剂表面的吸附性能,并考察了O2对C2H4吸附性能的影响.结果表明,Pd-Cu/SiO2具有与Pd/SiO2数量相近的表面Pd原子.加入Cu可使Pd对H2和CO的强吸附位数目相对减少,弱吸附位数目相对增加.Pd增加了H2在Cu/SiO2催化剂表面的吸附量,加速了O2在Cu表面的吸附速率.Pd原子和Cu原子在Pd-Cu/SiO2中混合均匀且分散良好.乙烯在Pd/SiO2表面吸附有乙川、di-σ和π吸附态.Cu的加入可抑制乙烯在Pd表面解离吸附为乙川,促进了非解离的di-σ和π吸附态形成.乙烯在室温下可与Pd表面吸附氧发生氧化反应,加入Cu可降低Pd表面吸附氧的氧化活性,使乙烯在Pd表面有效活化

关键词: 乙烯, 吸附量热, Pd-Cu/SiO2催化剂

Abstract: Adsorption of H-2, CO, O-2and C-2H-4on m(Pd)/m(SiO-2)=2%, m(Pd,Cu)/m(SiO-2)[n(Pd)/n(Cu)}=1/1]=2%, m(Pd,Cu)/m(SiO-2)[n(Pd)/n(Cu)=1/4]=2% and m(Cu)/m(SiO-2)=8%, catalysts was investigated by using the techniques of microcalorimetric adsorption at room temperature.The effect of O-2on adsorption of C-2H-4on the surface of the catalysts was also studied.It is found that the number of sites for H-2adsorption on PdCu/SiO-2is close to that on Pd/SiO-2. Addition of Cu decreases the sites of stronger adsorption and increases the sites of weaker adsorption of H-2and COon Pd.On the other hand, Pd can promote the dispersion of Cu on SiO-2and accelerate the rate of O-2adsorption on Cu/SiO-2. These results suggest that Pd and Cu atoms are well mixed and Pd atoms are well dispersed in the PdCu/SiO-2catalysts.Ethylene adsorbed on Pd/SiO-2produces ethylidyne and σ and di-π species.The addition of Cu inhibits the formation of the dissociatively adsorbed species--ethylidyne but promotes the formation of undissociatively adsorbed species--π and di-σ species for ethylene adsorption on Pd-Cu/SiO-2catalysts.Ethylene may react with O-2adsorbed on Pd/SiO-2at room temperature.Cu decreases the activity of adsorbed O-2on Pd-Cu/SiO-2. Hence, ethylene may be activated effectively on PdCu catalysts.

Key words: Ethylene, Calorimetric adsorption, Pd-Cu/SiO-2catalysts

中图分类号: 

TrendMD: